<video> decode in hardware!

media/filters/gpu_video_decoder.h

+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef MEDIA_FILTERS_GPU_VIDEO_DECODER_H_
+#define MEDIA_FILTERS_GPU_VIDEO_DECODER_H_
+
+#include <deque>
+#include <list>
+#include <map>
+
+#include "base/memory/scoped_ptr.h"
+#include "media/base/filters.h"
+#include "media/base/pipeline_status.h"
+#include "media/base/pts_stream.h"
+#include "media/video/video_decode_accelerator.h"
+#include "ui/gfx/size.h"
+
+class MessageLoop;
+namespace base {
+class SharedMemory;
+}
+
+namespace media {
+
+// GPU-accelerated video decoder implementation.  Relies on
+// AcceleratedVideoDecoderMsg_Decode and friends.
+// All methods internally trampoline to the message_loop passed to the ctor.
+class MEDIA_EXPORT GpuVideoDecoder
+    : public VideoDecoder,
+      public VideoDecodeAccelerator::Client {
+ public:
+  // Helper interface for specifying factories needed to instantiate a
+  // GpuVideoDecoder.
+  class Factories {
+   public:
+    virtual ~Factories();
+    // Caller owns returned pointer.
+    virtual VideoDecodeAccelerator* CreateVideoDecodeAccelerator(
+        VideoDecodeAccelerator::Profile, VideoDecodeAccelerator::Client*) = 0;
+    // Allocate & delete native textures.  Return true on success.

[scherkus (not reviewing), 2011/12/06 00:27:44]

space out methods

[Ami GONE FROM CHROMIUM, 2011/12/07 00:03:04]

Done.

+    virtual bool CreateTextures(int32 count, const gfx::Size& size,
+                                std::vector<uint32>* texture_ids) = 0;
+    virtual bool DeleteTexture(uint32 texture_id) = 0;
+    // Allocate & return a shared memory segment.  Caller is responsible for
+    // Close()ing the returned pointer.
+    virtual base::SharedMemory* CreateSharedMemory(size_t size) = 0;
+  };
+
+  // Takes ownership of |factories| but not |message_loop|.
+  explicit GpuVideoDecoder(MessageLoop* message_loop,

[scherkus (not reviewing), 2011/12/06 00:27:44]

not explicit

[Ami GONE FROM CHROMIUM, 2011/12/07 00:03:04]

Done.

+                           Factories* factories);
+  virtual ~GpuVideoDecoder();
+
+  // Filter implementation.
+  virtual void Stop(const base::Closure& callback) OVERRIDE;
+  virtual void Seek(base::TimeDelta time, const FilterStatusCB& cb) OVERRIDE;
+  virtual void Pause(const base::Closure& callback) OVERRIDE;
+  virtual void Flush(const base::Closure& callback) OVERRIDE;
+
+  // VideoDecoder implementation.
+  virtual void Initialize(DemuxerStream* demuxer_stream,
+                          const PipelineStatusCB& callback,
+                          const StatisticsCallback& stats_callback) OVERRIDE;
+  virtual void Read(const ReadCB& callback) OVERRIDE;
+  virtual const gfx::Size& natural_size() OVERRIDE;
+
+  // VideoDecodeAccelerator::Client implementation.
+  virtual void NotifyInitializeDone() OVERRIDE;
+  virtual void ProvidePictureBuffers(uint32 count,
+                                     const gfx::Size& size) OVERRIDE;
+  virtual void DismissPictureBuffer(int32 id) OVERRIDE;
+  virtual void PictureReady(const media::Picture& picture) OVERRIDE;
+  virtual void NotifyEndOfStream() OVERRIDE;
+  virtual void NotifyEndOfBitstreamBuffer(int32 id) OVERRIDE;
+  virtual void NotifyFlushDone() OVERRIDE;
+  virtual void NotifyResetDone() OVERRIDE;
+  virtual void NotifyError(media::VideoDecodeAccelerator::Error error) OVERRIDE;
+
+private:

[scherkus (not reviewing), 2011/12/06 00:27:44]

add 1 space

[Ami GONE FROM CHROMIUM, 2011/12/07 00:03:04]

Done.

+  // If no demuxer read is in flight and no bitstream buffers are in the
+  // decoder, kick some off demuxing/decoding.
+  void EnsureDemuxOrDecode();
+
+  // Callback to pass to demuxer_stream_->Read() for receiving encoded bits.
+  void RequestBufferDecode(const scoped_refptr<Buffer>& buffer);
+
+  // Deliver a frame to the client.  Because VideoDecoder::Read() promises not
+  // to run its callback before returning, we need an out-of-line helper here.
+  void DeliverFrame(const scoped_refptr<VideoFrame>& frame);
+  void DeliverFrameOutOfLine(const scoped_refptr<VideoFrame>& frame);
+
+  // Indicate the picturebuffer can be reused by the decoder.
+  void ReusePictureBuffer(int64 picture_buffer_id);
+
+  // A shared memory segment and its allocated size.
+  typedef std::pair<base::SharedMemory*, size_t> SHMBuffer;

[scherkus (not reviewing), 2011/12/06 00:27:44]

struct SHMBuffer {
  base::SharedMemory* shm;
  size_t size;
};

Avoids code like:
it->second.first->first->Close();

[Ami GONE FROM CHROMIUM, 2011/12/07 00:03:04]

Meh.  I honestly don't think the replacement is much sexier, but done.

+
+  // Request a shared-memory segment of at least |min_size| bytes.  Will
+  // allocate as necessary.  Caller does not own returned pointer.
+  SHMBuffer* GetSHM(size_t min_size);
+  // Return a shared-memory segment to the available pool.

[scherkus (not reviewing), 2011/12/06 00:27:44]

nit: blank lines before // comments

[Ami GONE FROM CHROMIUM, 2011/12/07 00:03:04]

Done.

+  void PutSHM(SHMBuffer* shm_buffer);
+
+  PtsStream pts_stream_;

[scherkus (not reviewing), 2011/12/06 00:27:44]

I'd like to get rid of this class -- did you find out a way to avoid using it?

[Ami GONE FROM CHROMIUM, 2011/12/07 00:03:04]

Not really, although the way I use it is pretty much as a heap.  I think
pts_{stream,heap}.{h,cc} could probably be collapsed a lot...

+  StatisticsCallback statistics_callback_;
+
+  // TODO(scherkus): I think this should be calculated by VideoRenderers based
+  // on information provided by VideoDecoders (i.e., aspect ratio).
+  gfx::Size natural_size_;
+
+  // Pointer to the demuxer stream that will feed us compressed buffers.
+  scoped_refptr<DemuxerStream> demuxer_stream_;
+
+  // MessageLoop on which to do fire callbacks and to which trampoline calls to
+  // this class if they arrive on other loops.
+  MessageLoop* message_loop_;
+
+  scoped_ptr<Factories> factories_;
+  // Populated during Initialize() (on success) and unchanged thereafter.

[scherkus (not reviewing), 2011/12/06 00:27:44]

nit: blank lines before // comments

[Ami GONE FROM CHROMIUM, 2011/12/07 00:03:04]

Done.

+  scoped_refptr<VideoDecodeAccelerator> vda_;
+
+  // Callbacks that are !is_null() only during their respective operation being
+  // asynchronously executed.
+  ReadCB pending_read_cb_;
+  base::Closure pending_flush_cb_;
+
+  // Status of the decoder.
+  bool flush_in_progress_;
+
+  // Is a demuxer read in flight?
+  bool demuxer_read_in_progress_;
+
+  // Shared-memory buffer pool.  Since allocating SHM segments requires a
+  // round-trip to the browser process, we keep allocation out of the
+  // steady-state of the decoder.
+  std::vector<SHMBuffer*> available_shm_segments_;
+
+  // Book-keeping variables.
+  typedef std::pair<SHMBuffer*, scoped_refptr<Buffer> > BufferPair;
+  std::map<int32, BufferPair> bitstream_buffers_in_decoder_;
+  std::map<int32, PictureBuffer> picture_buffers_in_decoder_;

[scherkus (not reviewing), 2011/12/06 00:27:44]

sanity check: do we need maps or if the count is low enough (isn't it like 3?)
would a vector of structs produce clearer code?

struct BufferPair {
  SHMBuffer* shmbuf;
  scoped_refptr<Buffer> buf;
  int32 id;
}
std::vector<BufferPair> buffers_in_decoder_;

mostly wondering if we can do away w/ all the first/second accessors code and
iterator soup if we know that we're dealing with at most 3 elements

[Ami GONE FROM CHROMIUM, 2011/12/07 00:03:04]

picture_buffers_in_decoder_ is always going to have <= 4 pairs, but
bitstream_buffers_in_decoder_ can have an unlimited number of them, and keeping
symmetry between these two variables seems better to me than introducing yet
another idiom to this class.

+  // picture_buffer_id and the frame wrapping the corresponding Picture, for

[scherkus (not reviewing), 2011/12/06 00:27:44]

nit: blank lines before // comments

[Ami GONE FROM CHROMIUM, 2011/12/07 00:03:04]

Done.

+  // frames that have been decoded but haven't been requested by a Read() yet.
+  std::list<scoped_refptr<VideoFrame> > ready_video_frames_;
+  int64 next_picture_buffer_id_;
+  int64 next_bitstream_buffer_id_;
+
+

[scherkus (not reviewing), 2011/12/06 00:27:44]

remove extra line

[Ami GONE FROM CHROMIUM, 2011/12/07 00:03:04]

Done.

+  DISALLOW_COPY_AND_ASSIGN(GpuVideoDecoder);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_FILTERS_GPU_VIDEO_DECODER_H_